My summer studentship at the University of Exeter was spent in the lab of Professor Sarah Gurr under the daily supervision of Dr William Kay. My project involved the investigation of parameters affecting the development of the fungal pathogen Fusarium oxysporum f. sp. cubense Tropical Race 4 (FOC TR4) – the causal agent of Panama disease in bananas. This project aimed to build upon knowledge surrounding the environmental conditions that affect this fungus, with wider applicability to the global issue of food security and farming.
F. oxysporum (FOX) is a ubiquitous soil microbe, with multiple pathogenic forms commonly associated with agricultural soils. FOC is a banana specific strain of FOX, of which TR4 is specific to the Cavendish cultivar. Cavendish bananas are the only globally exported cultivar of bananas and as such, this fungus proves a great threat to both food security and economic security in many parts of the world. TR4 first surfaced in southeast Asia in 1992 and has proliferated throughout the region since. It infects hosts by penetrating through the root into the vascular system causing wilting, yield loss and eventual death of banana plants. Three types of asexual spores; microconidia, macroconidia and chlamydospores, are each thought to fulfil specific roles during the infection cycle.
Over the course of my 10-week programme, my research involved exposing TR4 spore types to different physiological conditions and assessing germination, sporulation, growth and survival in vitro and in vivo. Conditions tested included temperature, light, pH, humidity and soil nutrition (including carbon: nitrogen balance). Through these experiments I learnt many laboratory techniques and methodologies. These included solid and liquid medium spore production methods, microscopy techniques such as brightfield and phase contrast, programming using the software ‘R’, and further molecular techniques such as DNA extractions, quantification methods, and gel electrophoresis.
The data collected have helped to highlight optimum and limiting conditions for FOC TR4. These results will allow me to build future predictive models of FOC activity in nature – a project I will undertake with Dr Dan Bebber for my undergraduate thesis this coming winter.
I would like to thank Professor Gurr, Dr Kay, and everyone in the Halpin Lab at the University of Exeter for their guidance, help and encouragement, as well as for allowing me to have the freedom to explore areas of investigation which I was most interested in. I would also like to give thanks to the BSPP for funding my research project, the whole experience has been extremely rewarding both academically and for my confidence as a biologist.
Rachel Piper
